Protective hood for a right angle grinder

ABSTRACT

A protective hood ( 1 ) for a right-angle grinder having a tightening device, which has a tightening band ( 4 ) firmly connected to the protective hood ( 1 ) for a right-angle grinder, the two ends ( 5, 6 ) of the tightening band being embodied as a first and second eyelet ( 7, 8 ), so that they form a first and second abutment ( 9, 10 ) and can be connected to one another under tension by means of at least two tightening elements, the first tightening element being a tightening lever ( 2 ), which with its first end ( 15 ) can be supported in the first eyelet ( 7 ) pivotably about a first axis ( 9   a ) and which can be brought into a first position in which the tightening device is not tightened, and into a second position in which the tightening device is tightened, becomes capable of being produced at less expense with still high quality by providing that the second tightening element is a spring ( 3 ), which can be connected movably to the tightening lever ( 2 ), the spring ( 3 ) being pivotably supported about a second axis ( 11 ) in the tightening lever ( 2 ) that does not coincide with but is parallel to the first axis ( 9   a ), and the spring ( 3 ) can be connected to the second eyelet ( 8 ) of the second end ( 6 ) of the tightening band ( 4 ), and the spring ( 3 ), on its end that can be connected to the second eyelet ( 8 ), has a straight region that is embodied as parallel to the second abutment ( 10 ).

BACKGROUND OF THE INVENTION

The Invention is based on a protective hood for a right-angle grinder.

From European Patent Disclosure EP 0 537 198 B1, a protective hood isknown that has a tightening device for tight fastening to the clampingneck of a power tool, in particular a right-angle grinder. Thetightening device is mounted on a tightening band, which is firmlyconnected to the protective hood. The ends of the tightening band areeach embodied as eyelets. The tightening device comprises a tighteninglever and a transmission member, and both the transmission member thetightening lever are each connected to one end of the tightening band insuch a way that they are each pivotable about a pivot axis embodied bythe eyelets. The transmission member is also supported pivotably in thetightening lever about a further pivot axis, and the three pivot axesare parallel to one another and do not coincide. As a result, intightening and loosening the tightening device functions like a togglelever device. By means of such a design, it is possible to replace theprotective hood on the clamping neck of the right-angle grinder withoutusing additional tools, such as a screwdriver.

SUMMARY OF THE INVENTION

The protective hood for a right-angle grinder has the advantage over theprior art of a more economical design, and the advantage of theaforementioned prior art, that is, that the protective hood for aright-angle grinder can be removed from the right-angle grinder withoutusing an additional tool, is still possible.

Because the second tightening element is embodied as a spring, it ispossible to compensate for production variations in the components ofthe protective hood for a right-angle grinder. This is made possible toa certain extent by the elasticity of the spring. It is furthermorepossible for the tightening band to be bent open or compressed to agreater extent that was possible in the prior art, since the spring usedas the second tightening element does not constantly engage the endembodied as the second axis but rather engages it only in theprestressed state and in the tightened state. The protective hood for aright-angle grinder is then firmly connected to a right-angle grinder.

It is advantageous to embody the spring With an undulating form in adirection perpendicular to one of the axes. Production variations in thetwo ends of the tightening band, which are embodied as eyelets, and inthe tightening band can then be well compensated for. If the spring isof wire, then it can be produced especially easily, and compared with aleaflike spring, there is a saving in terms of weight.

Advantageously, the wire is bent such that its ends face one another andare parallel to the second axis and assume the contour of a flatrectangular body. This increases the certainty that the spring will notslip out of the tightening lever.

It is furthermore advantageous if the undulating shape of the spring hasdifferent amplitudes, and if the spring has a shape that is symmetricalto a plane of symmetry that is vertical to the second axis. Such springsare simple to produce and because of their symmetry they cooperateespecially well with the other elements of the tightening device.

It is also advantageous if the first end of the tightening lever has aneccentric leg, which is embodied eccentrically to the first axis and isassociated with a first shoulder of the tightening band in the region ofthe first eyelet, with which shoulder it can be brought into a contactposition to limit the opening angle and as security againstunintentionally emerging from the first eyelet.

It is advantageous as well if a lug protrudes past the inside face ofthe tightening band and/or if a convex curvature is provided on theinside face of the tightening band. On the one hand, this assures axialsecurity against loss of the protective hood for a right-angle grinder,since the lug can engage a groove on the clamping neck. On the other,the convex curvature prevents torsion of the protective hood for aright-angle grinder relative to the clamping neck in the azimuthdirection relative to the pivot axis of the work spindle.

It is especially advantageous if the lug and the convex curvature aredisposed one above the other in a direction parallel to the first axis.As a result, they can be produced very simply and in only a singleoperation, for instance by stamping.

Further advantageous features of the invention will become apparent fromthe dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in further detail in the ensuing descriptionin terms of an exemplary embodiment shown in the drawings. Shown are

FIG. 1, a view of an exemplary embodiment of a protective hood for aright-angle grinder, seen from above;

FIG. 2, a perspective view of the protective hood for a right-anglegrinder of FIG. 1;

FIG. 3, a spring, seen from the same direction as in FIG. 1;

FIG. 4, a perspective view of the spring of FIG. 3;

FIG. 5, a view of the spring from the direction marked V in FIG. 3;

FIG. 6, a view of the tightening lever on a larger scale, seen from thesame direction as in FIG. 1;

FIG. 7, a view of the enlarged tightening band on a larger scale, seenfrom the opposite direction from FIG. 1;

FIG. 8, an enlarged detail of the tightening band of FIG. 7; and

FIG. 9, a perspective view of the tightening band of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a protective hood 1 for a right-angle grinder, on which atightening band 4 is mounted. The tightening band 4 is firmly connectedto the protective hood 1 for a right-angle grinder, for example by beingwelded to it. The tightening band 4 has two ends 5, 6, which areembodied as first and second eyelets 7, 8, respectively. A one-armedtightening lever 2 that has a handle 2 a is pivotably supported in thefirst eyelet 7. The tightening lever 2 also has an eccentric leg 2 b,which protrudes eccentrically past the first eyelet 7. A spring 3 ispivotably supported in the tightening lever 2 about a second axis 11,which is embodied as parallel to the first axis 9 a and does notcoincide with it. The tightening lever 2 and spring 3 form a tighteningdevice, by means of which the tightening band 4 can be drawn together. Alug 18 produced preferably by stamping protrudes past the inside face 17of the tightening band 4.

FIG. 2 shows a perspective view of the subject of FIG. 1; as anadditional characteristic, not visible in FIG. 1, a radiallyinward-pointing convex curvature 19 can be seen on the tightening band4. This convex curvature 19 is located below the lug 18. For furtherdetails of these two elements, preferably made in the same stampingoperation, see the description of FIGS. 7 and 8.

The protective hood 1 for a right-angle grinder is shipped in apreassembled state. In that state, the free end of the spring 3, thatis, the end not connected to the tightening lever 2, is alreadysuspended from the second eyelet 8. After the spring 3 was suspended inplace, the second eyelet 8 was compressed, so that the spring 3 can nolonger slip out of the second eyelet 8. As a result, an opening 4 a isformed by the tightening band 4, the tightening lever 2 and the spring 3suspended in the second eyelet 8. This opening 4 a can no longer be bentopen, in its diameter, beyond a certain 1predetermined value. Thisprevents the protective hood 1 for a right-angle grinder from being ableto be set onto a right-angle grinder for which the hood, because of itssize, is not intended.

The mounting of the above-described protective hood 1 for a right-anglegrinder on a right-angle grinder (not shown) proceeds such that theopening 4 a formed by the tightening device 4 is slipped onto a clampingneck (not shown) of the right-angle grinder, so that the lug 18protrudes into an annular groove (not shown) embodied on the clampingneck. Then the tightening lever 2 is pivoted about the first axis 9 a,which is embodied by an axial bolt 16, away from the tightening band 4,so that the spring 3, pivoting about the second eyelet 8 of thetightening band 4, follows the motion of the tightening lever 2. In theprocess, the spring 3, with a straight region 3 a (see FIGS. 4 and 5)that serves as an axis, engages the second eyelet 8 and is pivoted aboutthe second axis 11 in the tightening lever 2. If the tightening lever 2is then pivoted back toward the tightening band 4, the region 3 a of thespring precesses against the second abutment 10. In this position, thetightening device is in its prestressed state. The tightening lever 2 isthen pivoted farther in the direction of the tightening band 4, so thatthe two ends 5, 6 of the tightening band 4 are drawn together by thetightening device, acting as a toggle lever, comprising the tighteninglever 2 and the spring 3. This decreases the diameter of the opening 4 ain the tightening band 4, and the lug 18 engages the radial groove inthe clamping neck of the right-angle grinder. The tension of thetightening band 4 around the clamping neck is Increased steadily in thetightening process, so that the tightening band 4 is pressed so hardagainst the damping neck that a connection between the right-anglegrinder and the protective hood 1 for a right-angle grinder that issecure against relative rotation is assured. The tightening deviceembodied as a toggle lever system does not come loose on its own,either, because of the tension in the tightening band 4, since thetightening lever 2 in the process of tightening the tightening band 4moves past a dead center point beyond which a radial force relative tothe opening 4 a must be exerted to make the tightening lever 2 move pastthis dead center point again in order to loosen the tightening band 4.The dead center point is reached when the second abutment 10, the firstaxis 9 a and the second axis 11 are located in the same plane.

Removing the protective hood 1 for a right-angle grinder from theright-angle grinder is done in reverse order from mounting it. As aresult, it is possible without using a tool, such as a screwdriver, toconnect the protective hood 1 for a right-angle grinder securely andreliably to a right-angle grinder.

The tightening device comprising the tightening lever 2 and spring 3 aswell as the tightening band 4 are adapted to the particular size ofclamping neck. By the use of the spring 3, it is advantageously possibleto compensate for production variations both in the tightening band, forinstance in terms of the design of the two eyelets 7, 8 located on itsends 5, 6, and in the tightening device, that is, the tightening lever2, for instance with regard to its two axes 9 a, 11, and in the spring 3itself. As a result, such a protective hood 1 for a right-angle grindercan be produced very inexpensively and simply.

FIG. 3 shows the undulating shape of the spring 3. The undulating shapehas undulation crests and troughs 20, which are joined to one anothervia legs 20 a, 20 b. The undulations thus formed extend in a plane thatis vertical to the first axis 9 a and the second axis 11 and that isrepresented in FIG. 3 by the plane of the drawing. The spring 3 shownhas five crests and troughs 20, but this is in no way limiting, since agreater or lesser number of crests and troughs 20 can equally well beemployed. The undulation crests and troughs 20 each have the same radiusof curvature. Once again, this is merely one special design which is inno way limiting. The amplitude of the undulations varies, so that themiddle undulation has a greater amplitude than the other undulations.This is achieved by means of legs 20 a, 20 b of different lengths. Onceagain, this special design is not in any way to be considered limiting,since it is equally possible for all the amplitudes to be embodied asequal, or to provide more than two different amplitudes for theundulations.

In FIG. 4, it can be seen that the spring 3 is formed from a wire 12, inparticular a spring steel wire. The wire 12 is bent symmetrically to aplane of symmetry S (see FIG. 5), which is embodied parallel to theundulation crests 20. The two undulating parts of the spring 3, whichare embodied symmetrically to one another, are joined together at oneend of the spring via the straight region 3 a. The other end of thespring 3 is open, and the two ends 13, 14 of the wire 12 are bent suchthat they face one another and are oriented parallel to the twoundulating parts of the spring 3. At the same time, they are thusvertical to the straight region 3 a. When the spring 3 is inserted intothe tightening lever 2, then the straight region 3 a is parallel to thesecond axis 11, about which the spring 3 is pivotably supported in thetightening lever 2, and the two ends 13, 14 of the spring 3 are thenvertical to the axis 11.

In FIG. 5, it can be seen how the two ends 13, 14 of the spring 3 areembodied parallel to the plane of symmetry S and face one another. Thisdesign of the two ends 13, 14 of the spring 3 assures that in its statein which it is inserted into an opening 21 (see FIG. 6) in thetightening lever 2, and when it is prestressed as described above, thespring 3 cannot slip out of the opening 21 in the tightening lever 2.This is especially advantageous whenever the tightening lever 2 snapsopen, because it prevents the spring 3 from coming loose from thetightening lever and dropping to the floor and being lost. It can alsobe seen that the straight region 3 a is perpendicular to the plane ofsymmetry S. By the design of the straight region 3 a parallel to thesecond axis 11 and thus also to the second abutment 10 of the secondeyelet 8 of the second end 6 of the tightening band 4, it is assuredthat in tightening the tightening device, this straight region 3 a willrest with an accurate fit on the abutment 10, and thus secure tighteningof the tightening band 4 can take place.

In FIG. 6, the tightening lever 2 is shown on a larger scale. On itsfirst end 15, on which it can be connected to the first end 5 of thetightening band 4, the tightening lever 2 has the axial bolt 16, whichis embodied such that it extends parallel to the first axis 9 a when thetightening lever 2 is pivotably supported in the first abutment 9 of thefirst eyelet 7.

In addition, on its side remote from the handle 2 a, the tighteninglever 2 has the longitudinally protruding eccentric leg 2 b. This leg 2b, in its mounted state in the first eyelet 7, protrudes eccentricallypast the first axis 9 a. The tightening lever 2 has a U-shaped crosssection, and the two legs of the U between them grip the face ends ofthe tightening band 2 in the region of the first eyelet 7. The eccentricleg 2 b, as the tightening lever 2 opens, comes to a stop against afirst shoulder 22 (see FIGS. 7 and 9), so that as a result, both furtheropening and the possibility that the tightening lever 2 will be forcedout of the eyelet 7 are precluded. It is thus attained that in the openstate, the tightening lever 2 is secured against falling out of thefirst eyelet 7 of the tightening band 4.

The aforementioned opening 21 in the body of the tightening lever 2,into which the spring 3 is inserted., can also be seen. The second axis11, which is not physically present, about which the spring can bepivoted in its state in which it has been inserted into the tighteninglever 2, is located inside this opening 21. The second axis 11 isembodied parallel to the first axis 9 a.

FIG. 7 shows the tightening band 4 viewed from the opposite directionfrom FIG. 1. The embodiments of the two ends 5, 6 of the tightening band4 will not be addressed further here, because this has already beendescribed above in conjunction with FIGS. 1 and 2. The lug 18 and theconvex curvature 19, which protrude past the side face 17 of thetightening band 4, can be seen clearly. These two features are showneven more clearly in FIG. 8, which is an enlargement of the detail A ofFIG. 7. The lug 18 serves to prevent the protective hood 1 for aright-angle grinder from being able to slide axially along the clampingneck. Conversely, the convex curvature 19 serves to prevent torsion ofthe protective hood 1 for a right-angle grinder in the azimuth directionrelative to the pivot axis of the right-angle grinder, by means of agreater contact pressure of the tightening band 4 against the clampingneck. The two elements, that is, the lug 18 and the convex curvature 19,are disposed one above the other, in alignment, in an axis that isparallel to the first axis 9 a.

In FIG. 9, the first shoulder 22 on the tightening band 4, described inconjunction with FIG. 6, is shown. For its function, see the descriptionof FIG. 6. A second shoulder 23 is also embodied on the tightening band,in the region of the first shoulder 22 and parallel to it. On the otherend of the tightening band 4, adjacent to the second eyelet 8, a thirdshoulder 24 is formed, also oriented parallel to the first shoulder 22and the second shoulder 23. The second shoulder 23 and the thirdshoulder 24 serve to allow the spring 3 to pass freely through duringthe operations of tightening and loosening as the protective hood 1 fora right-angle grinder is mounted on a right-angle grinder.

What is claimed is:
 1. A protective hood (1) for a right-angle grinderhaving a tightening device, which has a tightening band (4) firmlyconnected to the protective hood (1) for a right-angle grinder, the twoends (5, 6) of the tightening band being embodied as a first and secondeyelet (7, 8), so that they form a first and second abutment (9, 10) andcan be connected to one another under tension by means of at least twotightening elements, the first tightening element being a tighteninglever (2), which with its first end (15) can be supported in the firsteyelet (7) pivotably about a first axis (9 a) and which can be broughtinto a first position in which the tightening device is not tightened,and into a second position in which the tightening device is tightened,characterized in that the second tightening element is a spring (3),which can be connected movably to the tightening lever (2), the spring(3) being pivotably supported about a second axis (11) in the tighteninglever (2) that does not coincide with but is parallel to the first axis(9 a), and the spring (3) can be connected to the second eyelet (8) ofthe second end (6) of the tightening band (4), and the spring (3), onits end that can be connected to the second eyelet (8), has a straightregion that is embodied as parallel to the second abutment (10).
 2. Theprotective hood (1) for a right-angle grinder of claim 1, characterizedin that the spring (3) is embodied in undulating fashion in a directionperpendicular to one of the axes (9 a, 11).
 3. The protective hood (1)for a right-angle grinder of claim 1, characterized in that the spring(3) is of wire (12).
 4. The protective hood (1) for a right-anglegrinder of claim 2, characterized in that the wire (12) is bent suchthat its ends (13, 14) face one another and are parallel to the secondaxis (11) and assume the contour of a flat rectangular body.
 5. Theprotective hood (1) for a right-angle grinder of claim 2, characterizedin that the undulating shape of the spring (3) has different amplitudes.6. The protective hood (1) for a right-angle grinder of claim 1,characterized in that the spring has a shape that is symmetrical to aplane of symmetry (S) that is vertical to the second axis (11).
 7. Theprotective hood (1) for a right-angle grinder of claim 1, characterizedin that a lug (18) protrudes past the inside face (17) of the tighteningband (4) and/or that a convex curvature (19) is provided on the insideface (17) of the tightening band (4).
 8. The protective hood (1) for aright-angle grinder of claim 1, characterized in that the lug (18) andthe convex curvature (19) are disposed one above the other in adirection parallel to the first axis (9 a).